Treatment-Resistant Femoral Lymph Node Abscess Caused by Cat Scratch Disease: A Case Confirmed by Polymerase Chain Reaction.

Cat scratch disease (CSD), a zoonosis caused by Bartonella henselae, frequently presents as localized lymph node swelling near sites of inoculation, such as scratches or bites. Here, we report a rare pediatric case of CSD in an eight-year-old girl, manifesting as a treatment-resistant femoral lymph node abscess. The patient had a history of chronic exposure to domestic cats. Initial empirical therapy was ineffective, and serology alone was inconclusive. A definitive diagnosis was established by detecting B. henselae DNA using polymerase chain reaction (PCR) from lymph node tissue, aspirate, and serum samples obtained during incision and drainage. This case highlights the clinical utility of molecular diagnostic techniques, such as PCR, in atypical CSD presentations and supports their early use to improve diagnostic accuracy, guide appropriate therapy, and avoid unnecessary invasive procedures.